Bookcase



FIG. 1 is a top perspective view of a bookcase showing my new design;

FIG. 2 is a bottom perspective view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a rear view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a right side view thereof;

FIG. 7 is a top plan view thereof; and,

FIG. 8 is a bottom plan view thereof.

Broken lines in the drawings depict portions of the bookcase that form no part of the claimed design. 

CLAIM The ornamental design for a bookcase, as shown and described. 